The present invention relates to a process for the decaffeination of green coffee beans.
Commercially available processes for the production of decaffeinated coffee make use of organic solvents. The disadvantages of these processes reside either in the possible health hazard involved or in the inflammability of the solvents in question. For this reason other methods have been sought. One line of approach has been treating an aqueous extract, obtained either from green beans or from roasted coffee, with a material which is selectively adsorbent for caffeine, followed by regenerating the caffeine "loaded" material to recover the caffeine. For various reasons none of the processes proposed has been really successful up till now.
A discussion of the prior art is to be found in German patent application No. 2,600,492 and U.S. Pat. No. 4,031,251. The process described in that patent makes use of a non-ionogenic synthetic polymer resin with hydrophobic characteristics and having a dipole moment of less than 2.0 Debye, preferably less than 0.5 Debye. This process avoids the difficulties encountered in the process according to U.S. Pat. No. 3,108,876. According to U.S. Pat. No. 3,108,876, strongly ionogenic cation exchanging resins are used (column 2, lines 16-21), which change the ionogenic composition of the extract, thus, for example, the pH is drastically changed. Other difficulties, however, are introduced, which are related e.g. to the hydrophobic nature of the resin. It is considered necessary to introduce organic solvents in the process to regenerate the resin. This means that a process with the stated object to avoid organic solvents again must have recourse to such solvents and that the process is appreciably complicated.